224 StOLIA ZEYLANiCA. 



with my conclusions regarding the age of the oysters discovered in 

 the previous September. It was also found that the oysters trans- 

 planted to the Nachchikkuda enclosure in January had all been eaten 

 by fish. Another visit was made in June, mainly for the purpose of 

 making transplantations from the southern part of the main bed, 

 where the oysters were extraordinarily abundant. A brief survey 

 of the progress of the beds was then made, and the enclosure at 

 Nachchikkuda was again stocked with oysters after it had been 

 strengthened. The work in June was rendered difficult owing to 

 the strong winds and rough seas. In September ten days were 

 occupied in making a thorough survey of the lake. The oysters 

 proved to be thriving, and were present in large numbers. Once 

 more the Nachchikkuda enclosure had been raided by fish and every 

 oyster had been eaten. Transplantations from the southern portion 

 of the main bed were effected and seven hundred oysters were placed 

 on the Kapalturai bed, and a similar number in Nachchikkuda, 

 outside the enclosure. 



The survey of September, 1912, was made in great detail and with 

 much thoroughness. Two boats were requisitioned — the one in 

 which the writer worked w^as kmdly lent by Mr. Hodson, the 

 Assistant Government Agent at Trincomalee, and the other in 

 charge of Mi". Henry was a hired canoe. Both boats were ordinary 

 dugouts, without outriggers. The weather was favourable on the 

 whole. The series of divmgs were made along parallel lines running 

 S. 60° W. , and in all 217 stations were investigated. At each station 

 two divers worked for not mor^ than 5 minutes, and made about 

 ten descents each. It was found very difficult to take satisfactory 

 bearings owing to the low coast line, and in consequence a series 

 of landmarks are being erected at various points along the shore. 

 These are as follows : — Coconut tree trunks to carry a white flag at 

 Kodaipota, Kakkaimunai, mouth of the Tamblegam-aar, Peyaddi- 

 munai, Sallaimunai, Pataiaddimunai near Kumladdimaddam ; a 

 cairn of whitewashed stones at Sinna Vellai Kalmunai ; whitewashed 

 rocks at Periya Vellai Kalmunai, Maulankarai, and Semmalai. 



Generally speaking, it may be said that the oysters on the beds 

 are healthy, and given normal conditions a fishery in three years 

 should be assured. 



It is hoped that in a short time all the main points regarding the 

 bionomics of Placuna will be made clear. The result of 2 years' 

 systematic work by the present writer, together with the previous 

 information which had been obtained, have enabled us to solve 

 many problems which have a direct bearing on the question of the 

 improvement of the fishery. 



It is admitted that there are now three main difficulties which 

 stand in the way of the present attempt to improve the window- 

 pane oyster fishery at Tamblegam. I refer to the danger due to an 

 inflow of an excessive amount of fresh water; to the ravages of 



